Anticoccidial compositions

ABSTRACT

Compositions comprising a mixture of the antibiotic frenolicin B with halofuginone hydrobromide the anticoccidial agent, useful for the treatment and prevention of coccidiosis in animals and methods of treating coccidiosis are disclosed.

BACKGROUND OF THE INVENTION

The invention relates to the field of compositions useful for theprevention and treatment of coccidiosis in animals, methods of usingsuch compositions and animal comestibles containing such compositions.

Coccidiosis is a disease caused by microscopic protozoal parasitescalled coccidia, belonging to the genus Eimeria. The infection in thehost animals is initiated by ingestion, usually along with food, water,and/or fecal material, of Eimeria organisms in the sporulated oocyststage. When the ingested oocysts enter the intestine, the infectiousstage of the Eimeria soon develops from the oocysts and causes extensivedamage to the inner walls of the intestine and the cecum or "intestinalpouch." Cecal coccidiosis in chickens, for example, is caused primarilyby the organism E. tenella and results in the destruction of the cecallinings of the host.

A number of coccidiostatic agents are presently available for theprevention and/or treatment of coccidiosis. Still, many of these agentshave certain shortcomings. Animals treated with some of the knowncoccidiostats sometimes show reduced feed efficiency and lower weightgains than normal. Moreover, the development of resistance to the morecommonly used agents is becoming an increasingly significant problem;one which is becoming a limiting factor in successfully combatingcoccidiosis. Still other agents have very narrow safety and efficacyranges with resulting toxicity risks for treated animals, as well as forother farm animals and man by virtue of incidental or accidentalexposure or ingestion.

A napthoquinone antibiotic produced from Streptomyces roseofulvus,frenolicin B, has been shown to have some anticoccidial activity againstE. tenella in chickens (Omura, et al., J. Antibiotics, Vol. 38, No. 10,pp. 1447-8 (1985)). Frenolicin B has recently been shown to besynergistic in combination with ionophoric anticoccidial antibioticsagainst which Eimeria field isolates had developed resistance due to thechronic usage of these agents to combat coccidiosis. See U.S. Pat. No.4,839,382.

SUMMARY OF THE INVENTION

It has now been discovered that compositions that contain a combinationof frenolicin B and the anticoccidial agent halofuginone hydrobromideresult in significantly potentiated activity against coccidiosis causedby Eimeria that have developed resistance to this anticoccidial agent.The activity of the instant compositions is greater than would beexpected from a simple additive effect of the two components.

DETAILED DESCRIPTION OF THE INVENTION

The present invention is directed to compositions which are useful forthe prevention and treatment of coccidiosis in animals comprising amixture of frenolicin B and halofuginone HBr.

These compositions are especially useful by virtue of their potentiatedactivity against strains of Eimeria which have become resistant to theaforementioned chemical anticoccidials which have been approved for andused in the treatment of coccidiosis especially in poultry.

The compositions of the present invention, when administered to animalssuch as domestic animals and animals raised commercially for food suchas poultry, cattle, sheep and pigs, are effective in the prophylaxis andtreatment of coccidiosis. The frenolicin B synergistically interactswith the halofuginone component of the instant composition resulting ingreater activity against resistant coccidiosis. Another advantage of thepresent invention is that the use of the frenolicin makes possible theuse of reduced amounts of the active ingredients with resultingreduction in the risk of toxicity and the side effects typicallyassociated therewith such as adverse influence on feeding, water intake,and nutrient absorption.

The production and isolation from Streptomyces roseofulvus of thefrenolicin B utilized in the present invention is disclosed in thearticle by Iwai et al., J. Antibiotics, Vol. 31 no. 10, pp. 959-965(1978).

((+)-trans-7-bromo-6-chloro-3-(3-(3-hydroxy-2-piperydyl)acetonyl)-4-(3H)-quniazolinonehydrobromide) is a known and commercially available anticoccidial.

The individual components of the compositions of the present inventionare employed in relative amounts which are synergistic in combatingcoccidiosis-producing microorganisms and in particular against thosestrains which have developed resistance to the halofuginoneanticoccidial due to exposure over time to the latter.

The improved anticoccidial animal comestible compositions of thisinvention are prepared by mixing the active ingredient with suitablecarrier or diluent material generally used in animals feeds or drinkingwater.

The concentration of the active ingredient in an animal feed compositionof this invention can be adjusted to meet particular needs and may varyover a wide range. The limiting criteria of the concentration are thatthe minimum concentration is such that a sufficient amount of the activeingredients is provided to effect the desired control of coccidiosis andthe maximum concentration is such that the amount of compositioningested does not result in any untoward or undesirable side effects.Because of the potentiating interaction of the active ingredients of thepresent invention, the amounts of each component required, may usefullybe less than that which would ordinarily be considered the usualrecommended dosing level for the individual components if usedseparately as a coccidiostat. The amount of the halofuginone necessaryfor successfully combating coccidiosis may therefore be beneficiallyreduced. Thus, the potentiated halofuginone HBr component is typicallypresent in an amount of from about 25 to about 90%, and preferably 33%to 75% of the normal recommended dosing level for that antibiotic. Forexample, the approved recommended dosing level for halofuginone HBr inchicken for the prevention of coccidiosis would be about 3 ppm. Thecomposition in accordance with the present invention can accordinglycontain the halofuginone in amounts of from as little as about 1 ppm to3 ppm depending on the respective dose of frenolicin B, that is fromabout 33 to about 77 ppm.

The easiest way to administer the anticoccidials is by mixing them inthe animal's feed. However, the anticoccidials can be usefullyadministered in other ways. For example, they can be incorporated intotablets, drenches, boluses, or capsules, and dosed to the animals.Formulations of the antibiotic compounds in such dosage forms can beaccomplished by means of methods well-known in the veterinarypharmaceutical art. Of course, whatever the method or methods ofadministration, the two components of the anticoccidial composition ofthe present invention can be introduced independently so long as thesynergistically effective combination is ultimately dosed to the animal.

The most practical way to treat animals with the anticoccidial compoundsis by the formulation of the compounds into the feed or drinking water.Any type of feed may be medicated with the anticoccidial compounds,including common dry feeds, liquid feeds and pelleted feeds.

The methods of formulating drugs into animal feeds are well-known. It isusual to make a concentrated drug premix as a raw material for medicatedfeeds. For example, typical drug premixes may contain from about 2.0 toabout 150 grams of drug per pound of premix. The wide range results fromthe wide range of concentration of drug which may be desired in thefinal feed. Premixes may be either in liquid or dry formulations.Separately formulated premixes for each of the two components could beadded to a given feed lot to provide the composition of the presentinvention in the final medicated feed.

The formulation of animal feeds containing the proper amounts ofanticoccidial for useful treatment is well understood. It is necessaryonly to calculate the amount of compound which it is desired toadminister to each animal, to take into account the amount of feed perday which the animal eats and the concentration of antibiotic compoundin the premix to be used, and calculate the proper concentration ofantibiotic compound or of premix, in the feed.

The known methods of formulating, mixing and processing feeds which arenormally used in the animal feed arts are entirely appropriate formanufacturing feeds containing the anticoccidial compositions of thepresent invention. The compositions of the present invention aretypically effective in combating coccidiosis when administered toanimals in feed mixes containing the compositions in a concentration offrom about 35 ppm to about 75 ppm.

The following example is illustrative of the invention.

EXAMPLE Anticoccidial Activity Against Halofuginone HydrobromideResistant Field Strain of E. Tenella

Experimental Procedure

Two-week old Arbor Acres, Peterson Cross broiler chickens, obtained froma commercial hatchery and kept in wire-floored, electrically heated,battery brooders, were used in all studies. Male birds, selectedaccording to weight, were used in each group. The chickens weremedicated two days before infection and maintained on the medicated feeduntil the termination of the trial for a total medication period ofeight days. There were two replicates of eight birds each per treatment.

Eimeria Field Isolates

The E. tenella field isolate was recovered from a commercial broileroperation in North Carolina and forwarded to ASR. The intestinal sampleswere homogenized with a Waring Blender, suspended in 2.5% potassiumdichromate solution, sporulated at room temperature, and inoculated intoyoung susceptible, coccidia-free chicks for further oocyst collectionand species identification.

At appropriate post-infection times, 5 to 7 days, the birds weresacrificed, autopsied, and diagnosis of Eimeria species made, based onlocation site, and oocysts measurement. Oocysts were collected from theintestines of the passaged birds and sporulated.

In evaluating the efficacy of the fremolicin-B combinations, 3.0×10⁵sporulated oocysts were administered per bird. The sporulated oocysts,properlly agitated and suspended in sterile distilled water, wereinoculated in volumes of 1.0 ml directly into the chick crop by means ofa blunt needle attached to a calibrated syringe.

Criteria for Evaluating Anticoccidial Efficacy

At termination of the trails, the surviving birds were sacrificed,necropsied and scored for gross lesions. All birds that died during theexperiments were also necropsied; proper diagnosis was made, and theirgross lesions scored and recorded. The intestinal lesions were scored as0=normal, 1=slight, 2=moderate, 3=severe and 4=dead. The readingsobtained were summarized as average degree of infection (ADI).

In addition, bird group weight, feed intake, feed conversion andmortality records were kept.

Results

The results are set forth in Table 1 below:

                  TABLE 1                                                         ______________________________________                                        Anticoccidial Activity of Frenolicin-B in Combination with                    Halofuginone HBr against Eimeria tenella                                                Level    Weight   Feed  Lesion                                                                              %                                     Treatment (ppm)    Gain, %  Conv. Score Mortality                             ______________________________________                                        UUC       0        100      1.62  0.0   0                                     IUC       0        67       2.07  3.1   25                                    Frenolicin B                                                                            60       100      l.58  l.1   0                                     Halofuginone                                                                            3        68       2.25  3.3    37.5                                 HBr                                                                           Halofuginone                                                                              3 + 60 96       1.60  0.6   0                                     HBr + Freno-                                                                  licin-B                                                                       Halofuginone                                                                              3 + 30 98       1.68  1.6   0                                     HBr + Freno-                                                                  licin-B                                                                       Halofuginone                                                                            1.5 + 60 98       1.66  0.8   0                                     HBr + Freno-                                                                  licin-B                                                                       Halofuginone                                                                            1.5 + 30 102      1.63  1.7   0                                     HBr + Freno-                                                                  licin-B                                                                       ______________________________________                                    

We claim:
 1. A composition for combating coccidiosis in animals whichcomprises halofuginone hydrobromide and frenolicin-B, wherein theseingredients are present in amounts which in combination aresynergistically effective in combating at least one coccidiosis-causingstrain of Eimeria.
 2. A comestible for feeding to animals, whichcomprises an animal feed containing an anticoccidial compositioncomprising halofuginone hydrobromide and frenolicin-B, wherein thecombination of halofuginone hydrobromide is present in an amount fromabout 1 to about 3 ppm by weight of the animal feed and the frenolicin-Bis present in an amount which combined with the halofuginonehydrobromide is synergistically effective in combating at least onecoccidiosis-causing strain of Eimeria.
 3. The comestible according toclaim 2 wherein the amount of frenolicin-B is from about 33 to about 75ppm by weight of the animal feed.
 4. The animal feed additive premixcontaining an anticoccidial composition comprising halofuginonehydrobromide and frenolicin-B wherein said composition is present in anamount sufficient to provide from about 35 to about 75 ppm of saidcomposition in said animal feed.
 5. A method of combating coccidiosis inanimals, comprising orally administering to said animals a prophylacticor therapeutic amount of an anticoccidial composition comprisinghalofuginone hydrobromide and frenolicin-B in amounts which incombination are synergistically effective in combating at least onecoccidiosis-causing strain of Eimeria.